Selection of a numerical model to predict the flow in a fan with a cycloidal rotor

A fan with a cycloidal rotor (CRF) is a promising design for application in HVAC (heat, ventilation and air conditioning) systems. Despite the widespread use of the CRF design as a form of propulsion, there are practically no scientific publications examining the possibility of using it as the HVAC fan. The choice of the cycloidal rotor facilitates the operating procedure and widens the range of operating conditions. The paper focuses on the use of the CRF in HVAC, especially as a blowing machine integrated with rectangular ducts, presenting, and discussing the search for the most efficient numerical model. The way of discretizing the computational domain, the turbulence models and the time integration method were tested. A four-blade open rotor fan with a cycloidal impeller was used both in the numerical and in the experimental model. The 2D and 3D CRF models created in the Ansys CFX package were adopted. After a mesh-independence study, different turbulence models were tested for the selected mesh. In the case of the 2D model, various turbulence models such as the SST and the RNG k-ε options were tested and compared with each other. The computational fluid dynamics simulations were compared with in-house experimental results of the velocity field measurements performed by means of laser Doppler anemometry and thermoanemometry. It turned out that the considered numerical models did not reflect the experimental measurements quantitatively. This may be due to the small differences in the shapes of the cycloids of the rotor blades in the numerical model and in real geometry.